Study: More species invasions in Great Lakes

Traverse City, Mich. (AP) – Dozens of foreign species could
spread across the Great Lakes in coming years and cause significant
damage to the environment and economy, despite policies designed to
keep them out, a federal report says.

The National Center for Environmental Assessment issued the
warning in a study released this week. It identified 30 nonnative
species that pose a medium or high risk of reaching the lakes and
28 others that already have a foothold and could disperse
widely.

Among them are fish such as the tench (“doctor fish”), the
monkey goby and the blueback herring.

“These findings support the need for detection and monitoring
efforts at those ports believed to be at greatest risk,” the report
said.

It described some of the region’s busiest ports as strong
potential targets for invaders, including Toledo, Ohio; Gary, Ind.;
Duluth, Minn.; Superior, Wis.; Chicago and Milwaukee.

Exotic species are one of the biggest ecological threats to the
nation’s largest surface freshwater system. At least 185 are known
to have a presence in the Great Lakes, although the report says
just 13 have done extensive harm to the aquatic environment and the
regional economy.

Perhaps the most notorious are the fish-killing sea lamprey and
the zebra mussel, which has clogged intake pipes of power plants,
industrial facilities and public water systems, forcing them to
spend hundreds of millions on cleanup and repairs.

Roughly two-thirds of the new arrivals since 1960 are believed
to have hitched a ride to the lakes inside ballast tanks of cargo
ships from overseas ports.

For nearly two decades, U.S. and Canadian agencies have required
oceangoing freighters to exchange their fresh ballast water with
salty ocean water before entering the Great Lakes system. Both
nations recently have ordered them to rinse empty tanks with
seawater in hopes of killing organisms lurking in residual pools on
the bottom.

Despite such measures, “it is likely that nonindigenous species
will continue to arrive in the Great Lakes,” said the report by the
national center, which is part of the Environmental Protection
Agency.

Some saltwater-tolerant species may survive ballast water
exchange and tank flushing, it said. And aquatic invaders could
find other pathways to the lakes _ perhaps escaping from fish farms
or being released from aquariums.

The report does not predict which species might get through.
Instead, it urges government resource managers to monitor waters
under their jurisdiction in hopes of spotting attacks in time to
choke them off.

“Early detection is crucial,” said Vic Serveiss, a scientist
with the National Center for Environmental Assessment and the
report’s primary writer.

The researchers compiled their list of 58 potential invaders by
reviewing scientific literature. They used satellite data and
computer modeling to produce maps predicting how 14 of the species
might spread across the Great Lakes, depending on availability of
suitable habitat.

The models suggested that Lake Erie _ shallowest of the lakes –
and the shallower portions of the other lakes were most vulnerable
to invasions.

Shallow areas tend to be warmer and have a greater variety of
life than deeper water, said Mike Slimak, an associate director of
the national center.

Hugh MacIsaac, a University of Windsor biologist and director of
the Canadian Aquatic Invasive Species Network, said he expected
very few invaders to reach the Great Lakes in ballast water now
that both nations are requiring tank flushing at sea. Flushing and
ballast water exchange should kill 99 percent of organisms, he
said.

“I would be very surprised if their prediction comes true,” he
said, referring to the EPA report’s suggestion that numerous
invaders could reach the lakes despite the new ballast rules.

The report reinforces the need for further measures to keep
foreign species out, including requiring onboard technology to
sterilize ballast tanks, said Jennifer Nalbone, invasive species
director for the advocacy group Great Lakes United.

“We are only beginning to invest the tremendous amount of
resources needed,” Nalbone said. “We’re being hammered by invasive
species and are still woefully behind.”